In an ac circuit, a resistance of 25 Ω is connected in series with an inductor of inductance 5 mH. If the phase angle between voltage and current is π/4, the value of inductive reactance will be
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 25 Ω
In a series LR circuit the voltage leads the current by the phase angle \( \phi \) given by the ratio of reactance to resistance.
\( \displaystyle \tan\phi = \frac{X_L}{R} \)
\( \displaystyle X_L = R\tan\phi = 25\,\Omega\times\tan\frac{\pi}{4} \)
\( \displaystyle X_L = 25\,\Omega\times1 = 25\,\Omega \)
The inductance (5 mH) is not needed, because the frequency is not given; the phase angle alone fixes \( X_L \).